News in Brief: DOAC interaction with PPI; COVID-19 vaccine for haemophilia patients; Billion dollar fine for clopidogrel claims

Thursday, 18 Feb 2021

 DOAC failure due to PPI interaction 

Doctors are warning clinicians to watch for potential, previously unreported DOAC interactions with PPIs following a case report of sub therapeutic anticoagulation with dabigatran.

The latest case, published in a letter to the editor of Internal Medicine Journal, describes an 81-year old male patient on dabigatran for AF. He was also on diltiazem at the time time of presenting to the ED with stroke. Despite responding well to an anti thrombotic regimen that included idarucizumab followed by intravenous alteplase, and reporting good adherence to dabigatran and omeprazole on discharge, the patient had another stroke just two days later.

Doctors from New Zealand who reported the case said the patient’s thrombin time (TT) fell after starting omeprazole indicating sub-therapeutic anticoagulation. The finding has prompted speculation of a likely mechanism of treatment failure – in this case  a drug–drug interaction between dabigatran and omeprazole, they cautioned.

COVID-19 vaccine recommendations for haemophilia patients

An Australian expert group has backed international guidelines on managing COVID-19 vaccination in patients with haemophilia.

The consortium of expert groups, including the World Federation of Hemophilia, who assembled the panel say there are no ‘specific contraindications’ to vaccination related to complications of haemophilia and other bleeding disorders or their therapies including for patients on immunosuppressive agents.

Among the 13 recommendations, which have been endorsed by the Australian Haemophilia Centre Directors’ Organisation (AHCDO), is advice for patients with severe or moderate haemophilia. These patients should only be given the vaccine after a factor VIII (FVIII) or factor IX (FIX) injection.

Patients with Type 1 or 2 Willebrand disease (VWD) should use therapies, such as DDAVP if available and tranexamic acid, in consultation with their haemophilia treatment centre, depending on their baseline von Willebrand factor (VWF) ristocetin cofactor (RiCof) activity levels. Patients with Type 3 VWD however, should be given a VWF-containing injection, the guidelines advises.

Other recommendations include performing prothrombin time testing in all rare bleeding disorder patients on anticoagulants to determine that patients are stable and within the therapeutic range 72 hours before vaccination.

The full guidance can be accessed here.

Billion dollar fine for clopidogrel marketers

Drug manufacturers Bristol-Myers Squibb and Sanofi have been ordered to pay more than US$834 million (AUD 1.076 billion) to the state of Hawaii for illegally marketing their blockbuster blood-thinner, clopidogrel (Plavix), by failing to disclose it may not be properly metabolised in people of Asian or Pacific-Island decent.

In a 43-page ruling the Judge presiding over the case said the drug makers knew there was a significant issue regarding a decreased response to clopidogrel among non-Caucasian patients. He said the companies ‘deceptive’ marketing practices ‘knowingly placed Plavix patients at grave risk of serious injury or death in order to substantially increase their profits.’

Read more here.

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